Organic Light Emitting Diodes (OLEDs) display panels have advantages such as faster response speed, higher color purity, brightness and contrast ratio and wider viewing angle as compared with conventional liquid crystal display panels, and thus have attracted more and more attentions from display technology developers.
FIG. 1 is a schematic diagram showing a partial structure of a conventional OLED display device. A plurality of sub-pixels P arranged in an array form a display region AA, a gate driver provide scan signals to each row of sub-pixels P in the display region AA by scan lines SL, and a source driver provides data signals to each column of sub-pixels P in the display region AA by data lines DL.
In order to save costs, the source driver in FIG. 1 includes a plurality of signal output portions MUX (for example, a plurality of multiplexers), each of which provides data signals to a plurality of data lines. A switch is provided on each data line. For example, each signal output portion MUX in FIG. 1 provides data signals to six data lines, and the data lines are provided with switches, respectively, which are driven by driving signals SW1 to SW6. FIG. 2 is a diagram showing timing of the driving signals SW1 to SW6 in FIG. 1. After one row of sub-pixels are turned on (time period of t1), the driving signals SW1 to SW6 can control the switches to enable one signal output portion MUX to provide display data for six data lines in a time-sharing manner.
The writing of data signals in the conventional technologies is unidirectional, that is, the writing of data signals can only be performed from low level to high level. After the switches are turned off, the data lines may maintain a part of the written data. If a high-level data signal (for example, 6V, black state), is written into a data line in a previous frame, after the switch corresponding to the data line is turned off, the high-level data signal can be partially maintain on the data line. Then, if a low-level data signal (for example, 3V, white state) is to be written into the data line in the current frame, after the switch is turned on, the data signal to be written in the current frame may not be written into the data line successfully. As a result, display abnormality may occur during the brightness switching from black to white.
To address the above problem, one technical solution in prior arts is as shown in FIG. 2. Specifically, for every frame, before the data signal is written (the time period of t2), the switches on all the data lines are turned on by the driving signals SW1 to SW6, and each of the signal output portions MUXs provides data signals of the lowest voltage to remove the residual data signal on each data line in the previous frame. This can avoid the problem that low-level data signals cannot be written. However, this technical solution results in increased complexity in timing of the driving signals and power consumption of the source driver.